DNA and Protein Synthesis - BioTopics Website
Ribosome feedback regulation, and growth rate-dependent controls of rRNA synthesis remain to be determined despite numerous investigations. r-protein. REGULATION OF RIBOSOMAL PROTEIN SyNTHESIS. control of ribosomal synthesis can be considered in relation to three basic problems 75.
What is the role of mRNA in protein synthesis? - …
i.ρ-dependent Termination: In some prokaryotes, the termination of transcription is helped by a ρ (rho) protein that gets attached at the 5′ end of the newly synthesizing mRNA. The ρ then moves along the mRNA and induces the formation of hairpin loop near the 3′ end of mRNA due to the presence of inverted repeated sequences. This helps in the detachment of mRNA from the DNA (Fig. 8.9).
Since protein is the major constituent of any cell, growth regulation is closely related to the control of ribosome synthesis. In fact, the number of ribosomes per. Protein genes suggests that ribosomal protein synthesis may be regulated in. 1980, to control for differential loading of RNA on each gel lane. Because the. Ribosomal assembly requires three or four separate ribosomal RNA rRNA molecules as well as ~50–80 ribosomal proteins r-proteins; the exact numbers.
Biology Review (DNA/RNA and Protein Synthesis ..
The process of synthesis of RNAs (mRNA, tRNA and rRNA) from DNA by the enzyme RNA polymerase is known as transcription. At the time of transcription, the RNA polymerase binds with double stranded DNA (gene) at a particular site (in prokaryotes known as promoter site) and after unwinding of the two strands of DNA by the rotation of the DNA, it starts copying one of
the two strands, known as coding strand (sense strand or template strand). The other strand of the DNA, which is not copied for the RNA synthesis, is known as non-coding strand (antisense strand) (Fig. 8.6).
DNA and Protein Synthesis - ScienceDirect
The termination of transcription occurs due to the presence of certain terminator sites on DNA. In prokaryotes, the termination is mainly done by in two ways, which involves the presence of certain palindromic sequences (Inverted repeats with the same sequences on the two strands of DNA when read in 5’→ 3′ direction. Thus, the presence of complementarity of bases on the same strand causing loop formation in mRNA due to intrastrand complementary base pairing) on DNA near the termination signals (Fig. 8.7 and 8.8).
Protein synthesis begins with DNA
In prokaryotes, the transcription and translation processes occur simultaneously as there is no nuclear membrane to separate the genetic DNA and the cytoplasm.
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In eukaryotes, the termination sites in DNA are present far away from the corresponding actual 3′ end of mRNA, thus, to produce HnRNA (heterogeneous nuclear RNA). The 3′ end of the mRNA is generated after the processing of HnRNA by snurp (small nuclear RNA-protein complex). In addition to these extra nucleotides at 3′ end, the HnRNA may also contain extra nucleotide sequences at the 5′ end and at the internal positions. These extra nucleotide sequences at internal positions are called introns, whereas, the nucleotide sequences in between the introns
The sequence is a small part of a gene that codes for a protein
that are present in mRNA and contain the information of proteins are known as exons. Thus, HnRNA produced after transcription is quite longer than the mRNA. Most of the extra nucleotide sequences, including introns, are cleaved by snurp. Moreover, after removal of the extra nucleotides from the 3′ end of the HnRNA, poly A tail is added that is required for the stability of the mRNA. Similarly, after removal of extra nucleotides from the 5′ end, a cap of 7-methyl guanosine (7mG) is added that is required for the translation process. The production and processing of HnRNA occurs in the nucleus from where it escapes into the cytoplasm through nuclear pores for the translation process (Fig 8.11 and 8.12).